I've discovered a downside. Apparently, devices connected to a cell tower will share the same IP. When I tried to download a file from a file sharing site, it told me I couldn't because that IP was already downloading. Not a big issue for me. Shows you that more people are also tethering as their main internet source right in my immediate vicinity.
With regards to performance, I must say I'm very very impressed. I was previously running on a 25mbps pipe and I still saw lag in loading sites. It wasn't the instant URL to Website that I expected from such a fast connection. I still get a very comparable experience. Sites load in a second or two.
Regarding heat, my iPhone was toasting hot but only when I had it hooked up via USB. That's likely from trying to keep the battery charged while doing some relatively intense data pushing. When I tether via Bluetooth, the phone is only moderately warm.
If it were possible to share a Rogers data plan with more than one device, I'd get an iPad3G and never have to get another ISP.